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spindrift??

I have heard of spindrift and coriolis effect and figure you guys are the people to talk to. Are these really factors to deal with at 1000 yards or less?
 
Only if you feel your ability to account for the effects with changes to your sight settings is a challenge.

They're certainly far more predictable than wind-related effects.
 
Both of these should be very constant and will be accounted for when you sight in your scope.

If however you are trying to shoot records.

Spin Drift can however make your bullet more sensitive to some wind conditions. It will fight against the wind in one direction and travel with the wind in the other. If you spend enough time testing in the right conditions you may be able to identify how it effects the bullets fired with your loads in your gun and improve your groups. If you read Tony Boyers new book he briefly explains how to test for this.

Good luck.
 
Go to the JBM ballistics site and run your load thru his drift program with a 0 wind speed, with and without drift included. For my favorite 6BR load it is .6MOA @ 1000 yards. Not a bunch but if you have to dial in a long shot with no sighter...
 
For a technical explanation, get a hold of Bryan Litz's book, Applied Ballistics For Long Range Shooting, chapters 6 and 7. You can also contact him through Berger Bullets.

Gordy
 
Ok that kind of made sense, but what if you are shooting north west or south west or south east? what does that do for the Coriolis effect?
 
From http://www.appliedballisticsllc.com/index_files/SpinandCoriolisDrift.htm

Drift
"Having a left or right twist will change the direction of gyroscopic drift. Bullets fired from right twist barrels drift to the right, and vise versa by the same amount, typically 8-9 inches at1000 yards for small arms trajectories. "

Coriolis effect
"The Horizontal component depends on your latitude, which is how far you are above or below the equator. Maximum horizontal effect is at the poles, zero at the equator. The horizontal component doesn't depend on which direction you shoot. Typical horizontal Coriolis drift for a small arms trajectory fired near 45 degrees North Latitude is about 2.5-3.0 inches to the right at 1000 yards.

The Vertical component of the Coriolis effect depends on what direction you shoot, as well as where you are on the planet. Firing due North or South results in zero vertical deflection, firing East causes you to hit high, West causes you to hit low. The vertical component is at a maximum at the equator, and goes to zero at the poles. Typical vertical deflection at 45 degrees North (or South) latitude for a 1000 yard trajectory is the same as for the horizontal component: +2.5 to 3.0 inches (shooting east), or -2.5 to 3.0 inches when shooting west."
 

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